At present potable spirits are invariably produced by an initial fermentation process involving the fermentation of a carbohydrate rich feed stock to produce a wash having an alcohol concentration of between 6% and 12% weight for weight. This wash is then distilled to produce a distilled raw spirit containing an ethanol water mixture which may approach azeotrope strenght, and typically contain 92% weight for weight ethanol. The distilled raw spirit also contains various congeners such as fusel oils and higher alcohols which are carried over during the distillation process despite having higher boiling points.
When manufacturing a white spirit such as vodka or gin the distilled raw spirit may be subjected to further operations such as subjecting it to the hydroselection process in which the distilled raw spirit is diluted with water and then redistilled. This hydroselection process helps to remove the congeners that are unwanted in white spirit but substantially increases the energy requirements for distillation. The final spirit which is obtained is an ethanol and water azeotrope. This may then be passed through adsorbent material such as active carbon to remove the remaining congeners to provide a substantially pure ethanol in the production of vodka or receive further rectification and flavoring treatment in the production of gin. The final spirit is diluted with demineralised water before retail distribution. Alternatively the pure ethanol is used as a spirit base for fortification or in the production of other alcoholic drinks.
In the production of industrial ethanol when it is required to produce substantially water free ethanol this is usually achieved by adding a material such as benzene to the ethanol water azeotrope to provide a ternary system. Subsequent distillation of this ternary system provides substantially water-free ethanol. However, this substantially water-free ethanol is contaminated with benzene. Such contamination would be totally unacceptable in the preparation of a potable spirit.